Use the Intl extension for locale dependent components

[dtdesign]

• [x] Require the intl extension in PHP. #5047
• [x] Add support for the locale selection of languages.
• [x] Convert the relative timestamps to use Intl.*.
  • [x] Account for the drift between the server and the client clock.
• [x] Migrate server-side relative timestamps to the intl extension or migrate the relative timestamps to a web component.
• [x] Use intl plural rules.
  • [x] PHP
  • [x] TypeScript
• [x] Format numbers using intl.
  • [x] PHP
  • [x] TypeScript